Chronic grass eaters

[Sue, Murphy and Bella ()*o*()]

Both my doodles love to eat grass. They snack on it off and on, all day, everyday, all year long. We have two types of grass, summer and winter types and they don't have a preference. Just keep chomping away.
They do not vomit hardly at all. Bella does about once every few months, but there's usually a sock, paper, plastic, poop or some other non digestible item in there, but rarely any grass. They both poop out the grass regularly without any problems. I'm wondering if it's a diet /nutrient need of some sort???
Does anyone else have doodles who just like to eat grass, totally unrelated to self inducing vomiting?

[Sue, Murphy and Bella ()*o*()]

Aww Quincy, what are you doing to your mama?

[F, Calla & Luca]

My two appear to always spit out the sticks TG.

[Allyson, Peri & Taquito]

Peri too...she just shreds and spits them out.

[J and Riley (and Luna)]

Luna too - she's more of a wood chipper than a termite.

[Sue, Murphy and Bella ()*o*()]

It does seem like Bella likes to chew them and swallow more than Murphy. He just chews and spits out. How can they be so different? Like kids I guess.